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6fd7f88
Add CSR YAML file for Ssqosid:srmcfg
syedowaisalishah Apr 23, 2025
08084a3
Add Extension YAML file for Ssqosid
syedowaisalishah Apr 23, 2025
091c477
Merge branch 'main' into add-ssqosid-csr-yaml
syedowaisalishah Apr 27, 2025
ffcce03
Add Extension YAML file for Ssqosid
syedowaisalishah Apr 27, 2025
cdadf98
Add CSR YAML file for Ssqosid:srmcfg
syedowaisalishah Apr 27, 2025
bed59a8
Merge branch 'riscv-software-src:main' into add-ssqosid-csr-yaml
syedowaisalishah Apr 30, 2025
cefa26a
docs(csr): improve srmcfg register description and field details
syedowaisalishah Apr 30, 2025
10cc9f0
Merge branch 'main' into add-ssqosid-csr-yaml
syedowaisalishah May 2, 2025
2693eec
docs(csr): improve srmcfg register description
syedowaisalishah May 2, 2025
9af87be
Update .gitignore
syedowaisalishah May 2, 2025
b22aea6
Add CSR YAML file for Ssqosid:srmcfg
syedowaisalishah Apr 23, 2025
ee25208
Add Extension YAML file for Ssqosid
syedowaisalishah Apr 23, 2025
084c743
Add Extension YAML file for Ssqosid
syedowaisalishah Apr 27, 2025
8ff0e7e
Add CSR YAML file for Ssqosid:srmcfg
syedowaisalishah Apr 27, 2025
9e9d9f2
docs(csr): improve srmcfg register description and field details
syedowaisalishah Apr 30, 2025
04e166e
docs(csr): improve srmcfg register description
syedowaisalishah May 2, 2025
f47a908
Merge branch 'main' into add-ssqosid-csr-yaml
syedowaisalishah May 8, 2025
9185363
Merge branch 'riscv-software-src:main' into add-ssqosid-csr-yaml
syedowaisalishah May 9, 2025
9484dc9
Merge branch 'add-ssqosid-csr-yaml' of https://github.com/syedowaisal…
syedowaisalishah May 9, 2025
abcd342
feat(csr): add YAML file for Ssqosid:srmcfg
syedowaisalishah May 9, 2025
12a4d9b
feat(csr): add YAML file for Ssqosid:srmcfg
syedowaisalishah May 13, 2025
73e1a92
Merge branch 'main' into add-ssqosid-csr-yaml
syedowaisalishah May 15, 2025
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2 changes: 2 additions & 0 deletions .gitignore
Original file line number Diff line number Diff line change
Expand Up @@ -21,3 +21,5 @@ __pycache__/
.pytest_cache/
*.bak
*.log
__pycache__/
*.pyc
43 changes: 43 additions & 0 deletions arch/csr/Ssqosid/srmcfg.yaml
Original file line number Diff line number Diff line change
@@ -0,0 +1,43 @@
# yaml-language-server: $schema=../../../schemas/csr_schema.json
$schema: csr_schema.json#
kind: csr
name: srmcfg
long_name: Supervisor Resource Management Configuration
address: 0x5C0 # Until the extension is finalized and assigned an official address by the RISC-V Foundation, srmcfg will use a placeholder/custom address
priv_mode: S
length: SXLEN
definedBy: Ssqosid
description: |
The srmcfg register is used to configure a Resource Control ID (RCID) and a Monitoring Counter ID (MCID).
Both RCID and MCID are WARL fields.

The RCID and MCID accompany each request made by the hart to shared resource controllers.
The RCID is used to determine the resource allocations (e.g., cache occupancy limits, memory bandwidth limits, etc.) to enforce.
The MCID is used to identify a counter to monitor resource usage.

The RCID and MCID configured in the srmcfg CSR apply to all privilege modes of software execution on that hart by default,
but this behavior may be overridden by future extensions.

If extension Smstateen is implemented together with Ssqosid, then Ssqosid also requires the SRMCFG bit in mstateen0 to be implemented.
If mstateen0.SRMCFG is 0, attempts to access srmcfg in privilege modes less privileged than M-mode raise an illegal-instruction exception.
If mstateen0.SRMCFG is 1 or if extension Smstateen is not implemented, attempts to access srmcfg when V=1 raise a virtual-instruction exception.

[Note]
A reset value of 0 is suggested for the RCID field, matching resource controllers' default behavior of associating all capacity with RCID=0.
The MCID reset value does not affect functionality and may be implementation-defined.

fields:
RCID:
location: 11-0
type: RW
description: |
The RCID is used to determine the resource allocations (e.g., cache occupancy limits,
memory bandwidth limits, etc.) to enforce.
reset_value: 0

MCID:
location: 27-16
type: RW
description: |
The MCID is used to identify a counter to monitor resource usage.
reset_value: 0
36 changes: 36 additions & 0 deletions arch/ext/Ssqosid.yaml
Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
# yaml-language-server: $schema=../../schemas/ext_schema.json

$schema: "ext_schema.json#"
kind: extension
name: Ssqosid
type: privileged
long_name: Quality-of-Service Identifiers
description: |
Quality of Service (QoS) is defined as the minimal end-to-end performance guaranteed in advance by a service level agreement (SLA) to a workload.
Performance metrics might include measures such as instructions per cycle (IPC), latency of service, etc.

When multiple workloads execute concurrently on modern processors—equipped with large core counts, multiple cache hierarchies, and multiple memory
controllers—the performance of any given workload becomes less deterministic, or even non-deterministic, due to shared resource contention.

To manage performance variability, system software needs resource allocation and monitoring capabilities.
These capabilities allow for the reservation of resources like cache and bandwidth, thus meeting individual performance targets while minimizing interference.
For resource management, hardware should provide monitoring features that allow system software to profile workload resource consumption and allocate resources accordingly.

To facilitate this, the QoS Identifiers extension (Ssqosid) introduces the srmcfg register,
which configures a hart with two identifiers: a Resource Control ID (RCID) and a Monitoring Counter ID (MCID).
These identifiers accompany each request issued by the hart to shared resource controllers.

Additional metadata, like the nature of the memory access and the ID of the originating supervisor domain,
can accompany RCID and MCID. Resource controllers may use this metadata for differentiated service such as a different capacity allocation for code storage vs. data storage.
Resource controllers can use this data for security policies such as not exposing statistics of one security domain to another.

These identifiers are crucial for the RISC-V Capacity and Bandwidth Controller QoS Register Interface (CBQRI) specification,
which provides methods for setting resource usage limits and monitoring resource consumption.
The RCID controls resource allocations, while the MCID is used for tracking resource usage.

versions:
- version: "1.0.0"
state: ratified
ratification_date: "2024-06"
url: "https://github.com/riscv/riscv-isa-manual/releases/tag/riscv-isa-release-5308687-2025-04-22"
requires: { name: S, version: ~> 1.13 }
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